In optical devices, for example in microscopes, there exists the need for the operator to introduce into the optical device, or remove from it, optical components such as mirrors, beam splitters, filters, lenses, gratings, prisms, or diodes, and to replace them with a different component from a series of available components, in which context the component must be positioned very precisely in the working position.
Sliders are known on which an optical component, e.g. a dielectric beam splitter, which can be introduced by the device user selectably into the beam path, is arranged. If that component is to be switched in only temporarily, a long slider having a first use position (called the “working position”′) and a second “parked position” in which the optical component is not effective, is advantageous. The component is switched by replacing the slider. The use position and parked position in the sliding direction are identified by a stop or detent. If one optical component of a series of possible ones is to be introduced into the beam path, sliders having components arranged next to one another, or wheels having components arranged circularly, are advantageous. In a situation with multiple components, a usable position in the sliding or rotational direction is identified by detents. Exact positioning in the beam path outside the sliding plane or rotational plane of the component being used is implemented, for example, by means of a precision dovetail guide or by pressure with a spring force against a reference surface.
DE-A1-197 02 754 discloses a filter switcher for microscopes, a filter mount being provided that is held reproducibly on a filter wheel by mechanical or magnetic auxiliary means. No information is provided as to the concrete nature and manner of operation of this magnetic holder, or its positioning on the filter wheel.
An objective turret for microscopes is evident from DE-A1-36 30 632. In order to mark various working positions, magnets that coact, or communicate, with magnetic field sensors for code recognition are attached to the turret shell.
US-B1-6 322 223 discloses optical components that are pre-installed on circular plates and can be positioned on a baseplate. Mechanical elevations on the underside of these sector plates coact with cylindrical element so as to make possible accurately oriented positioning on the circular plate. In addition, magnets are recessed into the sector plates and the baseplate. For example, one magnet corresponds with its north pole to a corresponding magnet with its south pole. Differently poled magnets are recessed on the baseplate. The result is that, in order to prevent transposition or incorrect orientation, each of the four sector plates can be placed at only one specific location on the baseplate. The approach of using identically poled magnets for deliberate repulsion operations is not evident from this document.
Also known, from DE-A1-197 23 74, is a laser cutting head that is attached to an upper housing by means of a magnetic holder. In the event of unintentional damage to the cutting head, this magnetic holder can function, so to speak, as a “defined break point”; in other words, the device can be deliberately pushed away from the housing. The type of magnetic holder is not discussed further; it can be assumed that it is an annular magnetic contact surface. Here as well, oppositely poled magnetic regions coact.
DE-U 1-200 01 763 describes a pair of eyeglasses or a mask that comprises a magnetic holder. The document depicts a front cover for a pair of eyeglasses and an eyeglass support element, the two detachably joined to one another by means of a groove-spring connection and said magnetic holder.
Lastly, W. Krause, “Konstruktionselemente der Feinmechanik” [Structural elements for precision engineering], VEB Verlag Technik, Berlin, 1st ed. 1989, pp. 450 and 451, discloses a magnetic detent system, the individual detent positions of a disk being secured in non-contact fashion.
The following aspects of this existing art are disadvantageous:
A dovetail guide can be produced only using complex manufacturing methods, since it requires close tolerances so that the component can be moved but nevertheless has no play. Pressing the component against a reference surface using a spring requires careful tuning of the spring force, and results in wear on both contact surfaces as a result of the pressure.
A magnetic holder using only one magnet, which is mounted either on the housing or on the displaceable part, has the disadvantage that in the usable position, magnetizable materials must be present opposite the magnet so that the magnetic force can act there; and no magnetizable materials must be used outside of that position, so that displacement is possible. With long sliders, the force of one magnet is often not sufficient to hold the slider in engagement against the reference surface. As a special instance of magnetizable materials, one or more magnets can also be mounted both on the housing and on the displaceable part so that they attract one another in a usable position. Mutually attracting magnets have the disadvantage, however, that they must be arranged above and below the reference surface and that, because they require space on either side of the reference surface, they can touch the beam path.